The Cook Islands education and tourism minister, Teina Bishop, has resigned just a day after early elections were called for July.
The MP from Aitutaki is expected to be replaced by Mona Ioane.
Mr Bishop, who was previously the marine resources minister, has been under police investigation for alleged bribery and corruption.
The former minister is being probed in relation to his connection with fishing company, Huanan Fishery.
Two months ago, Mr Bishop's Aitutaki home, his ministerial offices in Avarua and a unit in Nikau rented out by the Aitutaki MP were raided by officers.